Control circuit for multiple hydraulic press systems



Aug. 22, 1950 G. M. GEIGER ET AL CONTROL CIRCUIT FOR MULTIPLE HYDRAULICPRESS SYSTEMS Filed Dec.

George M 6121967 53% P/zz'l J lz'ndnefi attorn y Patented Aug. 22, 1950CONTROL CIRCUIT FOR MULTIPLE HYDRAULIC PRESS SYSTEMS George M. Geigerand Philip J. Lindner, Mount Gilead, Ohio, assignors to H-P-MDevelopment sCorporation, Mount Gilead, Ohio, a corporation of DelawareApplication December 10, 1948, Serial No. 64,472

Claims.

This invention deals with fluid-pressure-actuated apparatus, and in itsmore specific aspects, with hydraulic control circuits for hydraulicpresses or similar fluid-actuated apparatus.

The present invention has as its primary object the provision of animproved control circuit for multiple hydraulic press systems, wherein aplurality of presses are operated by pressure fluid displaced by asingle hydraulic pump, and wherein the individual control circuits ofthe presses are so arranged as to be locked-01f from the remainder ofthe control circuits, in order that the control circuit of eachindividual press may operate independently of the remainingpress-controlling circuits in the same manner as if each press-controlcircuit were supplied pressure fluid by separate pumping stations.

It is another object of this invention to provide a control circuit fora multiple hydraulic press system which make possible the operation of aplurality of presses in any desired order or sequence from a singlepumping station without fear of interference with the operation of anyone of the plurality of presses by the operation of another press in thecircuit.

It is a further object of the invention to proconduit I0, and at itsopposite end with a safety pressure relief valve H which functions inresponse to a predetermined maximum pressure within the supply line 9,to return fluid displaced by the pump to th reservoir 5. Disposed at oneend of the main pressure manifold It is a solenoid-operated two-Wayunloading valve l2, by which pressure fluid within the main'pressuremanifold it may be selectively exhausted to the reservoir 5. V

' Connected at intervals along the length of the manifold) are aplurality of separate branch conduits 13 in which are interposed checkvalves is which function to permit the flow of fluid in a direction fromthe pressure manifold Hi only.

.Connected to the outer ends of the branch conduits i3 are the fluidinlet ports {5 of a plurality of four-way distributing valves it. In theusual manner, the valves IS, in addition to the fluid inlet ports i5 areprovided with fluid outlets or exhaust ports ii, and first and secondmotor ports l8 and i9 respectively.

vide a control circuit for a multiple hydraulic press system whichembodies a pluralit of pressactuating hydraulic motors or rams each ofwhich is provided with advancing and retracting means to which pressurefluid may be supplied simultaneously during the pressing strokes of thepresses, in order to provide positive hydraulic pressure on both sidesof the pistons or plungers of the motors to prevent slippage or leakagewithin the motors during pressing operations.

For a. further and more detailed understanding of the present invention,and the various additional objects and advantages realized therefrom,reference is made to the following description and the accompanyingdrawing, wherein, the single figure is a circuit diagram disclosing themultiple press control circuit of the present invention.

Referring to the drawing, the present invention makes use of a liquidreservoir 5 in which a supply of hydraulic fluid is maintained to supplythe various fluid-actuated elements of the present control circuit, tobe hereinafter more fully described. Extending within the reservoir 5 isthe intake line 6 of a variable displacement uni-directional fluid pump1 having an output line 8. The output line 8 of the pump is connectedwith a supply conduit 9 which, in turn, is connected at one'end with apressure manifold vancing area 3!.

the armatures of solenoids 22.

Internally, the four-way valves it are provided with longitudinallyslidable spools 'or plungers 26 having end shafts 2| extendingexternally of the valve casing and connected with The plunger 20 of thevalve is normally spring-pressed to a neutral position by means of coilsprings 23, interposed between the ends of the plunger 2t and the endwalls of the valve casing, and upon selective energization of theassociated solenoids 22, the plunger is moved to positions providing forthe introduction of pressure fluid to either of the motor ports l-S andit while connecting the opposite motor port with the exhaust outlet ll.

Communicating with each of the motor ports 13 of the valves I6 is oneend of a supply conduit 24 which has its opposite end communicating withthe retracting chamber 25 of a fluidpressure-responsive motor orhydraulic ram 25.

Each motor or ram 26 comprises a cylinder 2? formed with an internalcylinder bore in which is reciprocably mounted a piston plunger 28having a ram-retracting pressure surface or area 2%, a primary advancingarea 36, and a booster ad- The cylinders 27of each ram are providedinternally with dome-shaped end chambers 32 through which extends anaxially disposed stationary booster plunger 33 formed with an axialpassage through which pressure fluid may be introducted to react uponthe boosteradvancing area 3| of the piston plunger. The end chamber 32of the cylinder 2? is provided with a pair of inlet ports 34 and 35through which fluid may be introduced to the end chamber or the cylinderto react upon the primary advancing pressure area of the piston plunger28. Connected with the inlet port of the end chamber is a conduit 35 inwhich is interposed a suction check valve 31 which functions to permitfluid contained within a, gravity-fed manifold 38 to be drawn inwardlyof the end chamber 32 as the piston plunger 28 advances under action ofthe booster plunger 33 to prefJl the primary advancing means of themotor.

Connected with the second motor port I9 of the valve 16 is a supplyconduit 39 which is connected at its opposite end with the bore or thestationary booster plunger 33. Communicating with the fluid inlet port35 of the cylinder 21 is a supply conduit 40 which has its opposite endcommunicating or connected with the motor port n of a three-waysolenoid-actuated valve 42. The valve 42 is provided with a fluid inletport 43 which is connected, by means of a branch conduit 44, with thesupply conduit 24 leading from the motor port 18 of the valve In to theretracting area of the individual motors 2B. The three-way valves 42 arefurther provided with fluid outlet or exhaust ports 35 which areconnected with an exhaust manifold as having a return conduit 41extending within the reservoir 5. The valves 42 are operable toselectively direct pressure fluid from thesupply conduits 24 to theconduits 40 associated with the main advancing area of the motors, or toconnect the conduits 40 and the advancing areas of the motors to exhaustby way of the exhaust manifold 46 and are preferably spring-pressed, bymeans of springs 42a to a position establishing communication betweenthe conduit 40 and the exhaust port 45, with the solenoid 42bfunctioning upon energization to shift the valve to its oppositeposition.

interposed within each of the conduits 40, be-

tween the valves 42 and the primary advancing area of the motors 28, isan adjustable pressure reducing valve 48 which is operable to variablyrediice the pressure of fiuid passing from the valve 42 to the primaryadvancing areas of the piston plii'ngers 2'8. Disposed in by passin'grelation to the pressure reducing valves 48 are check valves a providingfor the passage of fluid in a direction away from the motors and towardthe valves 42.

Thus, it will be seen, that as the distributing valves it areindividually conditioned to introduce pressure fluid within the conduits24, such fluid will normally be introduced within the retractin'g areaof the motors, but as the valves 42 are opened, the pressure fluid issimultaneously introduced within the primary advancing areas of themotors, and advancing movement of the piston plunger 28 will ensue, dueto the fact that the advancing area 30 is substantially greater than theretracting area 29 of the piston plungers. The pressure reducing valves48 associated with the primary advancing areas of the motors unction tocontrol the pressure of fluid introduced within the primary advancingareas of the motors, in order to determine the force exerted through thepiston plunger 28 to 'a press platen 49 carried at the outer endthereof.

In operation, assuming the piston pluhg'ers 28 to be in their inner-mostretracted positions, as shown in the drawing, the press cycle is begunby conditioning one of the valves IS SO as to direct pressure fluid fromthe pressure manifold 18 into the supply line 39 associated with thebooster" advancing area of the motors. At this time,

the retracting area of the motor will be opened to exhaust by way of anexhaust manifold Ila, thereby allowing the piston plunger 28 to advancerapidly under action of the booster advancing means. In the usualmanner, the booster ad- 'vancing plunger is utilized to speed theextension of the piston plungers into engagement or near engagement withthe work objects, and as the platen 49 carried by the piston plungers ofthe motor approaches the work, the valve [6 is shifted so as to directpressure fluid through the supply line 24 and to connect the boosteradvancing area to exhaust. Simultaneously, the valve #2 is conditionedby energizing solenoid 421) so as to connect the primary advancing areaof the motor with the supply line 24 whereby pressure fluid may beintroduced simultaneously into both the retracting area and the primaryadvancing area of the motor, at which time the piston plunger 28 movesin its pressing power stroke due to the differential in pressure areabetween the retracting area 29 and the primary advancing area 30. Theprovision of positive fluid pressure on either side of the head of thepiston plunger 28 insures a liquid-tight seal on either side of thehead, and prevents the passage of pressure fluid around the sides of thepiston plunger during its final pressing stroke.

As the piston plunger and platen reach their outermost position ofextension, and the pressing stroke is finished, th'evalve 42 isconditioned by (lo-energizing solenoid 42b so as to open the primaryadvancing area of the motor to exhaust, at which time the piston plunger28 will retract under pressure of fluid introduced to the 'retractingarea of the motor to once again return the piston to its innermostretracted position.

In this connection, it is important to note that during any stage of theoperation, of any one motor, another of the multiple circuits may be cutin to actuate another ram or motor without fear of diminishing theoperating pressure within the remaining press circuits, due to the factthat the check valves 14 will function to hold whatever pressure iswithin the individual motor control circuits, to prevent the release ofpressure backwardly through the pressure manifold I0 upon operation ofanother press circuit. Hence the present control circuit is particularlyadvantageous with respect to sequential press operations which requirethat one press after another be operated to one cycle of its overalloperation and stopped whereupon another oncuit is cut-in to conditionanother press for its particular cycle; it being understood that if apressure stroke is completed within one press, such ress may be held inits extended position without rear of slippage, due to the function ofthe check valves M, and their creation of a look within the individualcircuits. I

In view of the foregoing it will be seen that the present inventionprovides an improved and efficient control circuitfor a multiplehydraulic press system which utilizes but a single fluid displacementpump to supply pressure fluid to the individual press circuits forvariable sequential operation. Through the provision of the pressuremanifold and check valve system, the indi- 'vidual press-actuatingmotors or rams may be controlled independently of the remainingpressactuating rams in a manner to complete any partic'ular sequence orcycle of the ram operation, without fear of interference with suchoperation actuation of another of the ram circuits of the press system.

ass-grab Controlcircuits formed in accordance with the present inventionare further characterized by their structural simplicity, ease ofoperation and their economy of manufacture, maintenance and operation. 1a

While a single preferred embodiment of the present invention has beendisclosed in detail, it will be manifest that various modifications asto constructional details are possible without departing from the spiritof the invention or the scope of the following claims.

We claim:

1. In a hydraulic control circuit for a multiple station hydraulic presssystem; a plurality of hydraulic motors each comprising a cylinder, 2.piston plunger reciprocable in said cylinder and having a primaryadvancing area, a, retracting area and a booster advancing area, andmeans to introduce fluid to each of said areas; a source of fluidpressure; a pressure manifold to receive fluid pressure from saidsource; a, plurality of first valves separately connected with saidpressure manifold to selectively direct pressure fluid to ither theretracting area or the booster advancing area of each of said motorswhile connecting the other to exhaust; a plurality of second valvesconnected between said first valves, the retracting areas of saidmotors, and the primary advancing areas of said motors to selectivelydirect pressure fluid to the primary advancing areas of said motorssimultaneously with the introduction of pressure fluid to the retractingareas of said motors or to connect the primary advancing areas of saidmotors to exhaust; and check valves interposed betwe n each of saidfirst valves and said pressure manifold to prevent" the return of fluidfrom said first valves to said manifold.

2. A control circuit for a multiple station hydraulic press system,comprising a plurality of fluid-pressure-actuated motors each embodyinga cylinder, a piston plunger reciprocable in said cylinder and having aprimary advancing area, a retracting area and a booster advancing area,and means to introduce fluid to each of said areas; a fluid displacementpump; a pressure manifold connected to receive fluid under pressure ofsaid pump; a plurality of first valves connected respectively with saidpressure manifold, the retracting areas of said motors, and the boosteradvancing areas of said motors and operable to selectively directpressure fluid to either the retracting areas of said motors or thebooster advancing areas thereof while connecting the other to exhaust; aplurality of second valves connected respectively with the retractingareas, of said motors and the primary advancing areas thereof toselectively direct pressure fluid introduced to the retracting areassimultaneously to the primary advancing areas or to connect said primaryadvancing areas to exhaust; means connected between said second valvesand the primary advancing areas of said motors to vary the pressure offluid passing therebetween; and check valves interposed between each ofsaid first valves and said pressure manifold to prevent the passage offluid in a direction from said first valves to said manifold.

In a hydraulic press control circuit; a hydraulic motor having primaryadvancing means, retracting means, and booster advancing means; a sourceor fluid pressure; a first valve means to direct fluid under pressurefrom said source to either said retracting means or said boosteradvancing means while connecting the other to exhaust; a second valvemeans connected between said first valve ineans and said retractingmeans to direct pressurefiuid to said primary advancing meanssimultaneously with the introduction of fluid pressure to saidretracting means; and a check valve connected between said source andsaid first valve means to prevent the passage of fluid in a directionfrom said first valve means toward said source.

'4. A control circuit for a multiple station hydraulic press system,comprising a plurality of fluid-pressure-actuated motors each embodyinga cylinder, a piston plunger reciprocable in said cylinder and having aprimary advancing area, a smaller booster advancing area and aretracting area, and means to introduce fluid to each of said areas; afluid displacement pump; a pressure manifold connected to receive fluidunder pressure of said pump; a plurality of distributing valves eachhaving a fluid inlet connected with said pressure manifold, a fluidoutlet connected to exhaust, a first motor port connected with theretracting area of said motors, and a second motor port connected withthe booster advancing area of said motors, said distributing valvesbeing operable to selectively direct pressure fluid to either theretracting areas of said motors or the booster advancing areas thereofwhile connecting the other to exhaust; a plurality of second valvesconnected between the primary advancing areas of said motors and thefirst motor ports of said distributing valves to selectively directpressure fluid discharged through the first motor ports of saiddistributing valves to the primary advancing areas of said motorssimultaneously with the introduction of pressure fluid to the retractingareas thereof or to connect the primary advancing areas of said motorsto exhaust; means connected between each of said second valves and theprimary advancing areas of said motors to vary the pressure of fluidpassing between said second valves and the primary advancing areas ofsaid motors; and a check valve connected between each of saiddistributing valves and said pressure manifold to prevent the flow offluid in a direction from said distributing valves toward said pressuremanifold.

5. In a hydraulic control circuit; a hydraulic ram having a primaryram-advancing pressure area, a ram-retracting pressure area, and abooster ram-advancing pressure area; a fluid displacement pump; a firstvalve having connections with said pump, the ram-retracting pressurearea Of said ram and the booster ram-advancing area of said ram, andoperable selectively to introduce fluid under pressure from said pump toeither the ram-retracting pressure area or the booster ram-advancingarea while connecting the other area to exhaust; a second valve havingconnections with the ram-retracting area of said ram, the primaryram-advancing pressure area thereof and exhaust, and selectivelyoperable to hydraulically connect the ram-retracting pressure area withthe primary ram-advancing pressure area or to connect the primaryram-advancing area with exhaust; and a check valve connected betweensaid pump and said first valve to prevent passage of fluid in adirection from said first valve toward said pump.

GEORGE M. GEIGER. PHILIP J. LINDNER.

(References on following page) The following x aferences are, of recordin the file of this patent:

UNITED STATES PATENTS mama Dinzl ,2, 19 0 Nu ber n r'n i i at alnab-"2;;194. liarrin tqn QQQ- 22 17:17:17.7"Ef? FOREIGN PATENTS Country DateGreat Britain Apr. 10 L919

